I'm having some weird behavior with my wheelset. When I backpedal slowly, I can see the chain "bind" and hit the chain stay, then push the wheel to rotate backwards. If I backpedal quickly with force, the chain won't bind and the wheel will stay in place as I expect. I'm not riding a fixie!! Is there something up with my cassette body?

I have a chris king rear hub and I'm not sure what's wrong.. Some instructions on how to resolve this would be great. Am I supposed to clean the hub somehow?